Here’s another article and interview worth reading:
http://www.fqxi.org/community/data/articles/Lisi_Garrett.pdf
http://backreaction.blogspot.com/2007/08/garrett-lisis-inspiration.html
I should've linked to Lisi's own site in my post #1, but didn't. Here's the link:
Deferential Geometry (Garrett Lisi's website)